1. Field of the Invention
The present invention relates to signal processing, and more particularly, to a multicasting system for transmission of multimedia data.
2. Description of the Prior Art
In the prior art Video-on-Demand system (VOD system) for wireless transmission of real-time multimedia information, a typical VOD system includes at least one video content source, a content switch, and at least one video receiving terminal. Each VOD terminal has a dedicated channel that wirelessly sends a request via the content switch to the video content source for a desired video content. When a set of multimedia data, (for instance, a set of video file) is transmitted from the content source to a single user on a dedicated channel, the data rate can be adaptively modified based on the condition of the reception for that particular user's terminal. The better the condition of reception of the particular user's terminal the higher a bit rate at which the set of data can be transmitted to that user's terminal.
However, there are certain disadvantages associated with the prior art unicast VOD system. Indeed, for unicast system to be operational, one needs two dedicated channels for each user, one dedicated channel for reception, and one dedicated channel for continuously transmitting the condition of video reception back to the content provider. Thus, the given video content has to be transmitted over a number of channels twice as much as the number of users. Thus, the number of users is limited by the number of slots (or channels) that a wireless cell can support. A typical wireless cell is saturated very fast because the wireless cell can support only up to (5–50) video channels (that is up to (5–50) video users only), or up to (20–200) audio channels per cell, or up to (2–20) data channels per cell.
Thus, what is needed is to have a multimedia wireless system (for instance, a video system) that is free from the above-mentioned limitations. More specifically, what is needed is a multicast transmission system that can transmit data on the same channel for a plurality of smart terminals, wherein each smart terminal can independently and locally adjust the quality of received multimedia data without sending the feedback information to the content provider.